Parrot is a virtual machine designed to efficiently compile and execute bytecode for dynamic languages. Parrot currently hosts a variety of language implementations in various stages of completion, including Tcl, Javascript, Ruby, Lua, Scheme, PHP, Python, Perl 6, APL, and a .NET bytecode translator. Parrot is not about parrots, though we are rather fond of them for obvious reasons.

Cleaning up the Scheduler

In my work on Timers, I've concluded that the scheduler really is the right place for scheduling things (who would have guessed?). How the scheduler *should* work is described in pdd25. How the scheduler actually works is a bit different, and how I want the scheduler to work to implement green threads is a bit different from that...

A first optimization with PAST::Pattern, in detail

In my previous post, I described in tutorial form how to implement a very simple constant folding optimization for Integer addition. In this very brief post, I describe in greater detail how that optimization works.

A New Design for Timers

The next step in green threads is to make them preemptive: after one thread has run for a while, it needs to be stopped so a waiting thread can have a turn. Parrot has a mechanism for doing things after a set time called Timers which would be perfect for this. Unfortunately, they don't really work.

Progress, refactorings and tests.

Since my last post I haven't spent as much time as I'd like coding, since getting a win32 development environment setup was a bigger time sink than I expected, but I've still managed to stay pretty close to the schedule. The main feature for the next week, once I'm done with the charset-level stuff will be Iterators, which will finally enable NFG 'literals' in PIR source, for which I have added, failing, tests the past week.

GSOC NCI Updates

The NCI updates using the libffi are coming along. I ran into a bit of an annoyance when I found out that there are places internally where signatures are not specified for some functions, but luckily it was easy to remedy once I had figured out the problem. All of those cases used the same signature ("vJP"), it was only hard to find the right place to add that.

Adding Optimizations to HLL Compilers with PAST::Pattern

Parrot Abstract Syntax Trees(PASTs) are one of the forms code being compiled in a PCT-based compiler takes before being evaluated or compiled to bytecode. With PAST::Pattern, you can find all the sub-trees of a PAST that match a certain pattern and transform them. This can be used to perform optimizations at the PAST level.

It's Finally Time to Write Some Optimizations (Almost)

Wherein I dash your hopes of spending the weekend hacking on making your favorite HLL compiler generate better code only to give you hope at the end that it will not be long at all before you can:

The Last Week and a Half in PAST Optimization

I noticed yesterday that I forgot to post a blog post last week. I'll try to make up for that with double the blog post goodness this week(expect a second post Thursday or Friday).

Threads are continuations

Parrot has Continuations. In fact, Parrot is *based* on Continuations: rather than having a call stack and stack frames, each sub call has a return continuation - a pointer back to the call frame and bytecode position to return to after the sub completes.

As the Scheme and Ruby users keep telling us, continuations are pretty neat stuff. In fact they're so neat that they give us light weight cooperative threads "for free".

NFG is (somewhere in the vincinity of...) here

"N̈" (Or "n̈" if you don't like caps) is a grapheme from several minor extended Latin alphabets. It occurs in the orthographies of the Jacaltec Mayan dialect, Cape Verdean Creole, and in the rockumentary "This is Spın̈al Tap". Today I want to talk about the injustices this symbol has faced in the past and how, starting today, parrot can right them.

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